The present invention relates to a coil used in a paddle of an inductive charger coupling for charging a battery of an electric vehicle.
A typical inductive charger coupling for charging electrical vehicle batteries includes a paddle and a receptacle. The paddle is connected to an electricity supplying apparatus by a cable. When charging a battery, the paddle is plugged into the receptacle, which is located in the vehicle. The paddle includes a coil for transmitting electricity. The coil is wound about a core, which is located at a part of the paddle that is plugged into the receptacle. The receptacle includes a coil for receiving electricity. The receptacle coil is wound about a core, which is aligned with the paddle core when the paddle is plugged into the receptacle. Alternating current is supplied to the paddle coil when the paddle is plugged into the receptacle, which induces electricity in the receptacle coil. Accordingly, the vehicle battery is charged.
The paddle coil is made of a litz wire. The litz wire includes approximately one thousand twined and enameled strands, the diameter of each is, for example, 0.1 mm. The enameled strands are fastened by a coating of fine threads. The litz wire reduces heat. The paddle coil is formed by winding the litz wire about the paddle core, for example, four times.
When the paddle vibrates or receives a shock, adjacent parts of the litz wire rub one another. Also, since the fastening force of the thread coating is weak, the enameled strands scrape one another in the litz wire. Therefore, if the paddle is used for a long period, the thread coating of the litz wire and insulation coating of the enameled strands may be partially removed, which may cause a short circuit. To prevent parts of the litz wire in the coil and the strands in the wire from rubbing against one another, the litz wire may be covered by an insulating sheet and then impregnated with resin. This, however, complicates the manufacture and cannot sufficiently prevent the enameled strands within the coating from rubbing against one another.
Accordingly, it is an objective of the present invention to provide a coil used in a charging paddle that protects surface of a wire in the coil and prevents strands in the wire from rubbing against one another.
To achieve the above objective, the present invention provides a coil used in an inductive charging paddle. The coil is located about a core, which is located in the paddle. The coil is connected to an electricity supplying apparatus through a cable. The coil includes a wire having a bundle of strands and a coating for coating the wire. The coating includes a heat-shrinkable resin and is heat shrunk for holding the strands together.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.